So I go and start my 86 Reliant every once and awhile to keep everything going. But I like to check to make sure the a/c is still good but if I idle it too long in Park with a/c on the temp jumps up High. Of course I shut it off right away. I replaced the water hoses, coolant, and thermostat last year. The hoses both get hot, heater gets hot quick too. So I believe the water pump is still working good. There are no coolant leaks. I did look into the radiator and noticed a lot of calcium deposits on the cooling tubes. Probably from sitting for 11 years without being run. So what's the best way to get it clean or can you? I would hate to get caught at all the various traffic lights here and see the temp jump up especially on these blown head gasket prone 2.2's. I decided to use a flush chemical and I ran it for 30 mins and have let it sit a couple days to hopefully break some stuff up. I was planning on going and flushing with distilled water a couple times and then removing the radiator to see if it can be cleaned out by the radiator shop. Anything else I could try without having to buy a radiator? The fan does come on like it should when the a/c clutch engages. The a/c works great too.

Hi Its clear you've lost cooling capacity .... the rad shop is the best idea ....I just had the one in my truck done and what a difference!! If its a full copper rad the rad shop will be able to clean it ....the replacements I've seen all have plastic tanks and are not serviceable.

I used a Gumout flush chemical I had sitting around. I followed the instructions. I added the flush and let it run 10 minutes after reaching normal temperature with the heater on. It has yet to overheat sitting at Park in idle anymore but I drained the radiator out but instead of adding distilled water and running it another 10 minutes I actually took the radiator out. It looks really bad on the radiator fins. I've looked around online to see about possible cleaning solutions to let soak in it but nothing was trusted. I saw people use vinegar, baking soda, coke, and even CLR. I was thinking of CLR but figured it would be too caustic, which turns out to be true according to their website someone posted about. I took the radiator out and flushed it out good with the garden hose but it's got to be full and soak to break up some of the deposits. Is vinegar the best bet? It looks like if you lay it flat up and fill it up it will be able to soak. I'm sure it will cost just as much taking it to the radiator shop as buying a new aftermarket radiator. So if there is a way to clean it at home I would like to try it because it's a good radiator.

Hi I would think that any over the counter descaling product would be useless and I've never had any real success with the DIY automotive products which is why I usually get my rads overhauled. If you are intent on doing it yourself you could try a type of de-scaler intended for hard deposits but yet won't eat your radiator. I don't know of any reliable product so you'd have to look around ...The shop I deal with does good work as I've had a few rads built by them ...word is if its an all metal radiator it can be saved ... my cost for my truck rad cleaning was $150 to replace the rad would have been around $400. If the shop you know does this kind of work and you can afford it I'd just get it redone...but that's me .

I've searched online and vinegar seems to be the most widely used. The difference is most stories I've read involved using it as a flush. I've got my radiator out because I saw scale in it. I didn't see any when I took of the thermostat housing. So I'm just trying to clean up the radiator at the lowest cost. I don't plan on keeping the car much longer. I just wanted to get it running and repainted which I have. The furthest I've driven it before the overheating was 200 miles to a car show where it won which was summer of 2015 and it made it without any issues. It mostly sits outside and occasionally driven a few miles once and awhile to get it cleaned. I will try the vinegar to see if it loosens up. It's an all metal radiator.